// 上边框
@mixin border-top {
    background-image: $border-image-top;
    background-size: 100% 1px;
    background-repeat: no-repeat;
    background-position: left top;
}

// 下边框
@mixin border-bottom {
    background-image: $border-image-bottom;
    background-size: 100% 1px;
    background-repeat: no-repeat;
    background-position: left bottom;
}

// 上下边框
@mixin border-vertical {
    background-image: $border-image-top, $border-image-bottom;
    background-size: 100% 1px;
    background-repeat: no-repeat, no-repeat;
    background-position: left top, left bottom;
}

@mixin border-left {
    background-image: $border-image-left;
    background-size: 1px 100%;
    background-repeat: no-repeat;
    background-position: left top;
}
